Police, Protesters Standoff in Tunisia on 'Arab Spring' Anniversary

TUNIS, Tunisia — Police have stepped up security in Tunisia's capital amid protests against the government marking three years since a young vendor set himself on fire, leading to revolutions across the Arab world, known as the "Arab Spring."

The extremist Ansar al-Shariah movement, which has links to al-Qaida and is believed to have organized an attack on the U.S. Embassy, called for protests Tuesday at government headquarters in the Tunis casbah.